LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 139,304	$ 139,203
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	71,642	69,776
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	45,412	42,551
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	26,230	27,225
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	67,662	69,427
Retail | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	33,823	32,726
Retail | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	17,711	16,495
Retail | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	3,407	4,744
Retail | Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	8,550	10,812
Retail | Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 4,171	$ 4,650